Printing plate



R. R. LEWIS PRINTING PLATE Aug. 21, 1934.

Filed Feb. l5, 1953 CEMENT FBQ/C BOND/N6 BASE @emol/ed y fngml//r IN VEN TOR.

Il ab Patented Aug. 21, 1934 PRINTING PLATE Robert R. Lewis, Baldwin, N. Y., assignor to Vulean Proofing Company, New

York, N. Y., a

corporation of New York Application February 15, 193s, serial No. 656,772

'8 Claims.

My invention relates to a new and improved printing plate.

One of the objects of my invention is to provide a printing plate which has a rigid or flexible backing and which has a resilient and oil-proof surface, which can be carved and engraved so as to provide any desired design, which may be a relief design. 'I'he backing of the plate may be of any suitable type which will enable the l0 ,plate to be used in a printing press.

Another object of my invention is to provide an improved surface for carving and engraving, so that said surface will be unaffected by the oils, solvents or other chemicals, which are present in the ink or to which the plate is subjected in washing, and the like.

Another object of my invention is to provide a surface having a light color, so that the design to be engraved or carved can be transferred to said surface by means of regular transfer materials which produce the design in a dark color.

Another object of my invention is to provide a surface which has the desired properties of firmness in proportion to thickness, so that the design will not be squashed or distorted, when pressure is applied during the printing operation.

Another object of my invention 'is to provide a printing plate in which the depth of ,the engraving or carving is sufiicient to prevent the ink from piling up in the bottom of the engraved portion.

Another object of my invention is to provide a printing plate having a fabric insert which determines the depth of the engraving or carving, in the surface of the plate.

Another object of my invention is to provide a printing plate having a fabric insert which consists of two or more layers, a suitable number of such layers being selected, so that the engraving 40 can be carried through the top fabric insert, or

even down to the base of the printing plate. Ihis makes it poible to produce large open areas in the design.

Another object of my invention is to provide a surface which can be easily cut with the usual engraving tools, so as to produce a clean cut.

Another olgject of my invention is to provide an engraving surface whose yield under the pressure of the engraving tool or tools is limited, so

that fine detail can be secured.

Other objects of my invention will be set forth in the following description and drawing which illustrates a preferred embodiment of my invention, it being understood that the above general statment of the objects of my invention is intend- (Cl. lol-401.1)

ed merely to generally explain the same and not to limit it in any manner.

Fig. 1 is a diagrammatic sectional view.

Fig. 2 is a plan view showing one embodiment of the invention.

Fig. 3 is a sectional view Fig. 2.

Fig. 4 illustrates another embodiment of the invention.

Fig. 5 is a sectional view on the line 5 5 of 05 Fig. 4.

The improved printing plate has a base 3 which may be made of soft metal which can be readily j bent to the curvature of the plate cylinder of a'j rotary press, if this is desired. Said base should 10 be of uniform thickness` The base should be firm enough to hold its shape, when it is clamped on the bed-plate of a printing press, or when the improved printing plate is mounted upon a wood block. When the base is made of metal, I prefer to use the alloy later specified. Said plate may be made of a suitable condensation resin, such as bakelite, and said base can also be made of any' bendable or resilient material.

An intermediate fabric insert is connected to the base, and said fabric insert preferably consists of a plurality of layers. I prefer to use four such layers. If the base is made of a suitable metal or alloy, the total thickness of the plate should not exceed 0.156 inches, and said thickness should not be less than 0.150 inches. The use of a thickness which` exceeds 0.156 inches makes it difficult to avoid excessive pressure in the press, `and if the thickness is less than 0.150 inches, too much time is required for makeready. The coating of the plate which acts as a printing surface should be smooth, and said surface can be rubbed with sandpaper or emerycloth if pits or other surface defects develop. In addition to having the base of uniform thickness, the layers of fabric should also be of uniform thickness and the surface coating should also be of uniform thickness. 'I'he top and bottom layers of fabric are preferably different from the intermediate layers.

The top and bottom layers of fabric, which respectively abut the base and the surface coating, are preferably made from the material which is known as "Grade A Airplane Cloth which is made according to the following specifications: 105

Cotton, plain weave, 2 ply yarns both warp and f filling; min. thread count, warp, 80 filling; max. weight, 4.5 oz. per square yard; breaking strength, strip method, per inch-warp 80 lbs, filling 80 lbs.

80 on the line 3 3 o f -a main thread count of 48 warp threads per inch,

5A and 48 flller threads per inch.

The four layers of fabric are first combined or cemented by means of a rubber cementing compound, which is applied by means of the well known spreading machine, This rubber cementing compound should be fairly oil-resistant, but it should not be too sticky, so that the engraving may pentrate to or through any of the layers of fabric, if this is desired. A suitable rubber cementng compound can be made according to the following formula:

Rubber 30 lbs. Zinc nxide 25 lbS. 8 OZ. Antimony sulphide 5 lbs. 4 oz. Sulphur 3 lbs. Limp 6 oz. Diphenyl guanidine 51/2 oz. Stearic acid 1/2 oz. Phenyl-beta-naphthylamine; 6 oz.

In the above formula, the function of the zinc oxide is to activate the accelerator and reinforce the compound.

The function of the lime is to absorb small percentages of moisture, thereby avoiding porosity.

'I'he function of the stearic acid is to activate the accelerator.

, The other ingredients serve to vulcanize the rubber, and to act as vulcanization accelerators and anti-oxidants, in the usual manner.

'I'he improved rubber cement is applied to the surfaces of each of the fabric layers. A suiiicient amount` of the rubber'cement is applied as a coating between the four plies of fabric, so that the combined thickness of said four plies or layers and the intermediate layers of cement is 0.047 inches, when said four layers are connected. The cement compound is only applied to those surfaces of the fabric layers which are to be cemented to the surfaces of the other fabric layers.

The top surface of the fabric insert, to which the surface coating is to be applied, is treated with two or three spreader coats of a special bonding compound which firmly holds the surface coating during the printing operation, but permits the surface coating to be easily stripped during the engraving operations. This bonding for connecting the surface coating of the printing plate to the top surface of the fabric insert can be made by dissolving the following ingredients in gasoline after mixing them on a mill:

Rubber 50 lbs. Ceresin wax 2 lbs. 8 oz. Coumarone resin 10 lbs. Petrolatum 1 1b. 8 oz. Stearic acid 1 lb. Orange shellac 12 lbs. 8 oz. Tetramethylthiuram disulphide 2 lbs. Mercaptobenzothiazole 4 oz. Zinc oxide 1 lb.

In the above mentioned compound, the function of the wax is to enable the coating to separate readily from the base when the engraving is done.

The function of the coumarone resin is to y cause this bonding compound to penetrate the fabric and to adhere to it.

The function of the petrolatum is to soften the compound and to help release the coating after engraving.

'Ihe function of the stearic acid is to activate the accelerator.

The function of the orange shellac is to give the proper balance of adhesiveness and release.

The function of the zinc oxide is to activate the accelerator.

The other ingredients require no special discussion. l

The surface coating which is provided upon the fabric insert is of the type which is made by reacting ethylene dichloride and sodium polysulphide. 'I'his reaction produces a reaction plastic which is not affected by oil, printing ink, etc. This reaction plastic does not harden when it is heated, but the heat treatment increases they mechanic resistance of this compound. Other polysulphides, and other additive halogen compounds of an olefin may be used, instead of the substances which have been specifically mentioned. When the reaction plastic is masticated in a mill, it becomes plastic. The surface coating compound which is later referred to, and which contains said reaction plastic, can be applied at a temperature of about 200 F., on a three-roll calender.

In making the reaction plastic, the sodium, polysulphide may be replaced by the polysulphides of potassium, calcium, ammonium, or of any of the alkali or alkali earth metals.

'Ihe ethylene dichloride may be replaced by propylene dichloridespor by dichlorides of higher members of the olefin series. The dibromides may be used instead of the dichlorides.

Generally speaking, the reaction plastic is a polymerized substance derived from a halogenized unsaturated hydrocarbon in the presence of sulphur.

This surface coating is applied to the bonding coating of the fabric insert by means of a calender. I prefer to apply three coats of said surface coating, so that the surface coating has a total thickness of 0.028 inches. Said surface coating may be prepared in the usual manner by masticating the following on a two-roll mixing mill.

Ethylene dichloride sodium polysulphide reaction plastic 50 lbs. Vlinhher 5 lbs. Zinc oxide 11 lbs. Clay 1 15 lbs. Whiting 20 lbs. Diphenyl guanidine 3 OZ. Mercaptobenzothiazole 1 oz. Stearic acid 4 oz. Paraffln 4 oz. Methyl salicylate 1 lb. 8 oz.

because said base consists essentiallyv of the 50 pounds of the reaction plastic and the 5 pounds of rubber. The zinc oxide and the clay and the Whiting may be considered as filling materials. The function of the Whiting is to reinforce the compound.

The surface layer has a sufficiently large percentage of the reaction plastic so that it is unaffected by oils and printing inks. This may be defined by stating that the base of the surface layer consists substantially of the reaction plastic, although I do not wish to be limited to any specific proportion of the reaction plastic.

In the above mentioned formula, the function of the zinc oxide is to react with the reaction plastic during the heat treatment, in order to is not necessary, but it increases the calendering properties of the compound.

The function of the clay is to increase the strength and toughness of the compound.

The function of the stearic acid is to increase the calendering properties of the compound.

The function of the paraffin is to improve the calendering properties of the compound.

The function of the niethyl salicylate is to import a pleasant odor.

In applying the surface coating to the top of the fabric insert, great care must be exercised in order to avoid-trapping any air between the successive surface coatings. After the last surface coating has been applied, so that the surface of the printing plate has reached its final thickness, the outer surface of said surface coating is dusted with talc. The device is now stored for a period of at least forty-eight hours, at an ordinary room temperature of about F. This storage period is necessary in order to properly anchor the surface coating to the fabric insert. During this storage period the bonding compound mentioned herein hardens so that the surface coating is prevented from penetrating into the interstices of the fabric and adhering too tightly.

It will be noted that at this point the fabric insert has not been connected to the rigid or semirigid base so that the device is very flexible.

The device (without the base) is tightly wrapped around a large and hollow iron drum, the outer face of the surface coating being in contact with a rubber-coated fabric liner. That is, the liner is applied to the outer face of the surface coating, and the liner and the device are wrapped in a spiral around. said drum.

This spiral is now covered with two layers of a water-proof rubberized fabric, and said waterproof fabric is held in place by means of a spiralwrapping of any suitable narrow fabric. 'I'he device is therefore subjected to tension and pressure as it is tightly wrapped around the drum, and the liner subjects the outer face of the surface coating to suitable pressure. The device and the liner are Wrapped around the drum under considerable tension, in order to produce the desired conditions. The drum is now pushed into a horizontal steam-vulcanizer of the well-known type, and the device is now vulcanized in an atmosphere of steam according tothe following schedule: 45 min. at 220 F., 45 min. at 250 F., 45 min. at 270 F., and 11/2 hrs. at 287 F.

The extended heating and the gradual rise in temperature are desirable because it tends to heat the entire thickness of material at nearly the same rate, so that the middle portion will be heated at the same rate as the end which is against the drum, and the outer end.

Immediately after removal from the vulcanizer, the waterproof rubberized fabric is removed, and the device is unwound and separated from the liner. The device is then allowed to cool to an ordinary room temperature of about 70 F. and this cooling ordinarily takes about twenty-four hours. The surface of the device is then buffed and polished, so that its thickness is not less than 0.075 inches and does not exceed 0.078 inches. This buing operation provides the surface with a smooth outer face, and the thickness of said surface is rendered uniform.

The device can now be cut into pieces of any suitable size, and these pieces can be mounted upon the base. Each said piece is cut about one inch larger than the base, in both dimensions.

The form of printing plate is ordinarily rectangular or square, although any suitable form may be provided. The metal base is preferably made -from a rolled sheet of an alloy which is 0.070

inches thick and which composed of 87% of lead, 11% of antimony and 2% of tin. 'I'he metal bas vmay consist of lead alone, but this is rather soft. Likewise, the metal base may consist of zinc, but zinc is harder and more expensive than the preferred alloy. The sheets of metal which are used for forming the base of the device are prepared by Sandblasting the surface to which the fabric insert is to be applied. The top surface of the base and the back face of the fabric insert are then each given several coats of a suitable rubber cement, which has been dissolved in a suitable solvent. After the solvent has completely evaporated, the surfaces are pressed together for not less than twelve hours under a moderate pressure, which is about one-half pound per square inch. The excess material is now trimmed off. The cement which bonds the device to the metal base will increase the thickness to about 0.005 so that the final thickness of the printing plate will be between 0.150 inches and 0.156 inches.

The above mentioned printing plate is uniform, has a light surface color, has a smooth outer face, and all the parts are firmly connected to each other. The improved plate is impervious to and it is unaffected by solvents and oils, and it combines satisfactory engraving qualities and proper firmness for use in a printing press.

'I'he engraver may cut through the surface 110 coating to the top fabric layer, or he may cut through said fabric layers to any extent desired, even to the inner surface of the base.

The improved printing plate may be used for any kind of typographic printing with any kind of ink. The subject matter, 'of course, is limited to that which can be engraved by hand. The skill of the engraver determines the limitations.

It is to be understood that when the engraver cuts into the surface coating material, he removes the same in order to produce a design in relief. Likewise, the engraver may cut through the intermediate fabric insert, to any extent desired.

The final plate has a thickness made up as follows:

Thickness Base .070 inches.

Bonding layer which connects the bottom surface of the bottom layer of fabric to the base .005.

4 layers of fabric 3 lzycrs of cementwhich are located intermediate gfeapiaxrs of adjacent surfaces of the tout layers .047 mmm Top binding layers which connect the top surface of the top layer of fabric to the surface coating- Surface coating .028 inches.

Likewise, in some cases it is-sumcient to connect the surface coating' directly to a metal base by means of a suitable bonding material, thus eliminating the use of an insert.`

Referring` to Figs. 2 and 3, these show the four fabric inserts 2, 2a, 2b and 2c, and the surface coating 1. l In this embodiment the surface coating has been cut down to the top layer 2, so that this layer 2 is exposed. This embodiment is suitable where there are large open spaces; in the design, lettering, or the like.

In the embodiment shown in Fig. 4, the relatively small and closed area of the design has been formed by cutting away the surface coating 1 so as to leave the top layer 2 exposed. The relatively large open area of the design has been formed by cutting away the surface coating 1 and the two top layers 2 and 2a.

As previously stated, it would not be departing from the invention to cut the plate down to the base 3.

The purpose of the insert is to provide a resilient ,or cushion-backing for the printing surface 1.

for the bonding which connects the surface layer to the material below the same, I can use other waxes, and various resins,-for the ceresin wax which is specifically mentioned. Likewise, the petrolatum is merely illustrative of numerous oils and oily residues, mineral residues and the like,

which can accomplish the function of the petrolatum.

I claim: Y

1. A printing plate having a flexible surface printing layer, said surface layer including an oilresistant polymerized substance which is derived from a halogenized unsaturated hydrocarbon in the presence of sulphur.

2. A printing plate comprising a relatively rigid base, cushioning material connected to said rigid base, and a printing layer connected to said cushioning material, said printing layerincluding a flexible and oil-resistant surface layer which includes a-polymerized substance which is derived from a halogenized unsaturated hydrocarbon in the presence of sulphur. l

3. A printing plate comprising a relatively rigid base, a fabric insert connected to said base, and a printing layer connected to said fabric insert, said printing layer including a flexible and oilresistant surface layer ywhich includes a polymerized substance whichis derived from a halogenized unsaturated hydrocarbon in the presence of sulphur. j

4. A printing plate comprising a relatively rigid base, a plurality of fabric layers connected to each other and to said base, the top and bottom fabric layers being more tightly woven than the intermediate layer or layers, and a printing layer connected to the top fabric layer, said printing layer including a flexible and oil-resistant surface layer which substantially consists of a polymerized substance which is derived from a halogenized unsaturated hydrocarbon in the presence of sulphur.

5. A printing plate having a flexible and oilresistant surface printing layer, said surface printing layer containing at least 50% of a polymerized substance which is derived from a halogenized unsaturated hydrocarbon in the presence of sulphur.

6. A printing plate having a flexible and ollresistant surface printing layer, said vsurface printing layer consisting substantially of a poly--` merized substance which is derived from a halogenized unsaturated hydrocarbon in the presence of sulphur, and filling material.

. 7. A method of forming a printing-plate, which consists in spreading upon supporting material a bonding which has a major proportion of rubber, then spreading upon said bonding a surface layer which contains a flexible and oil-resistant polymerized substance which is derived from a halogenized unsaturated hydrocarbon in the presence of sulphur, and then storing the device until the surface layer has been anchored to the supporting material.

a. A method or making a printing plate which 

